The producers of “Outlander” are all about making the show as authentic as it can be.

That starts with shooting in the foggy hills of the Scottish Highlands — including turning real-life ruin Castle Doune into fictional Castle Leoch, home of the MacKenzie clan, whose exploits are recounted in Diana Gabaldon’s best sellers — garbing the men in real kilts, which are composed of some 10 yards of tartan and then folded by hand; and having the Scots speak Gaelic, the language of the time. That’s why resident hunk Jamie Fraser (Sam Heughan) often affectionately refers to Claire Randall (Caitriona Balfe) as “Sassenach,” which means “outlander” in Gaelic, a derisive term that Jamie turns into a pet name.

Since Gaelic is nearly a dead language, sprinkling it liberally through the scenes took some doing. For starters, the show hired Àdhamh Ó Broin to serve as the show’s Gaelic dialect coach.

The series, which has been renewed for a second season, was lucky to find Ó Broin. The married father of four has dedicated much of his life to the study and preservation of the language and its multiple dialects, and he brought that expertise to bear on “Outlander.”

“I grew up on the western coast of Scotland, where I was surrounded by Gaelic place names, so I was aware of it from a very early age,” he says.

As English became the pervasive language throughout Scotland, Gaelic began to die out. “My grandmother thought it was an injustice, and that someone in the family should learn it and bring it back,” he says. “Once I got a taste for it, I got bitten by the bug. For the past 10 years, it has been an obsession.”

Irish-born Galfe is the one member of the cast who knows the Gaelic language.Photo: Starz

The show is taking some risks with its use of the language, mainly by not subtitling it. However, Claire doesn’t speak Gaelic either, so there’s usually someone standing next to her translating. Ironically, Irish-born Balfe is the one person in the cast who actually knows Gaelic.

The ancient language came easier for some actors than others. Gary Lewis (“Billy Elliott,” “Gangs of New York”), who plays clan leader Colum MacKenzie, hails from Glasgow, and gives several long speeches in the language. Another Scotsman, Graham McTavish (“The Hobbit”) plays Colum’s powerful brother, Dougal, and he’s also frequently called on to speak in Gaelic.

“I wish I spoke Gaelic,” McTavish says. “It’s a beautiful language, but it’s a difficult one to learn.”

That’s where Ó Broin comes in, constantly coaxing sounds from the actors they’ve never previously made. He hopes that exposing millions of people to the language will help save it.

“If you want to destroy a people, destroy their language. It contains their entire history and their way of looking at the world,” he says. “It will be fantastic to have a whole new generation of people interested in Scotland, our language and our culture.”